1. Field of the Invention
The invention relates to an improved method and apparatus for detecting fecal or ingesta contamination on the carcasses of animals during and after slaughter using visible light fluorescent spectroscopy.
2. Description of the Prior Art
Microbial pathogens in food cause an estimated 6.5 million to 33 million cases of human illness and up to 9,000 deaths annually, according to the Council for Agricultural Science and Technology. Furthermore, the USDA Economic Research Service has recently reported that the annual cost of the food-borne illnesses caused by six common bacterial pathogens, Campylobacter spp., Clostridium perfringens, Escherichia coli 0157:H7, Listeria monocytogenes, Salmonella spp., and Staphylococcus aureus, ranges from 2.9 billion to 6.7 billion dollars (Food Institute Report, USDA, AER, December, 1996). The foods most likely to cause these illnesses are animal products such as red meat, poultry and eggs, seafood, and dairy products.
Contamination of meat and poultry in particular with many bacterial food-borne pathogens often occurs as a result of exposure of the animal carcass to ingesta and/or fecal material during or after slaughter. Any of the above-mentioned pathogens can be transmitted to humans by consumption of meat and poultry contaminated in this manner. However, the contamination of carcasses with feces or ingesta is the primary source of contamination of meat and poultry with particularly onerous pathogens, including Campylobacter spp., Escherichia coli 0157:H7, and Salmonella spp.
After slaughter, each carcass is examined for disease or evidence of contamination that would render all or part of the carcass unfit for human consumption. Currently, the meat packing industry relies upon a variety of methods for the inspection of animal carcasses. These methods typically include human visual inspection, microbiological culture analysis, bioluminescent ATP-based assays, and antibody-based microbiological tests. Unfortunately, these procedures are labor intensive, time consuming, and insensitive, and do not meet the needs of the packing industry for an accurate, high speed, non-destructive method that is amenable to inspection and real-time analysis.
Fluorescence spectroscopy has been commonly used for the analysis of a variety of compounds, microorganisms, and tissues. The use of fluorescence spectroscopy for the detection of contaminants on foods has also been previously disclosed. For example, Alfano (U.S. Pat. No. 5,474,910) disclosed a method and apparatus for detecting biological molecules and microorganisms by irradiating the sample material with UV light at a wavelength between about 250 to 325 nm and measuring the resultant fluorescence. Alfano further disclosed that the process could be used for detecting the bacterial spoilage of food products, including meat and poultry. More recently, Waldroup and Kirby (U.S. Pat. No. 5,621,215) disclosed a method and apparatus for detecting the contamination of meat or poultry with ingesta or fecal material. As described therein, the meat or poultry is illuminated with UV light having a wavelength between about 320 to 420 nm, and examined for fluorescence, specifically UV fluorescence. Despite these advances, there exists a continuing need for a high-speed system for detecting ingesta or fecal contamination of carcasses with increased sensitivity and accuracy.